1999 Polaris SLH, SLTH, SLX, SLTX, PRO785 Factory Service Manual, Page 260Get this manual
FINAL DRIVEJET PUMPBILGE SYSTEM VentilationCavitation Diagnostics If watercraft exhibits poor performance, high engine RPM with little forward speed or power, inconsistent RPMor difficulty pulling skiers out of the water, pump ventilation or cavitation may be the cause
Ventilation
Ventilation results when air enters the pump inlet tract and is compressed by the impeller, causing reduction in thrust and an increase in engine RPMSmall leaks are often difficult to diagnoseA hole or crack the size of pin in the sealed area around the pump intake tract is enough to cause ventilationSome possible sources of air are:
1Intake scoopAn improperly sealed intake scoop is the most common cause of ventilationMake sure the scoop has complete bead of Marine Grade silicone sealer all the way around without any gaps or pin holes Sometimes, small leaks in the silicone sealer around the intake scoop are hard to detect with visual inspectionThe following method may make it easier to seeSee page 5.11 for scoop installation1Turn high speed fuel screws out (counterclockwise) 12 turn, and operate the craftRemove intake grate and look for exhaust trail (black smoke path) in the area around the scoopRemove intake scoop and re-seal with complete bead of Marine Grade silicone sealantRefer to illustration below for critical sealing points in the pump area